The new Spiraea cultivar is a product of a planned breeding program conducted by the inventor, Timothy D. Wood, in Grand Haven, Mich. The objective of the breeding program was to produce new Spiraea varieties of compact and full habit with new and better flower and leaf colors. The open pollination resulting in this new variety was made during June of 2007.
The parents are unknown varieties of Spiraea japonica; seed was bulk collected and actual parents not identified. In a block of 100 mature, flowering, unnamed seedlings that had been pretreated with 10 greys of radiation, seed was collected from ten plants evaluated to have the best foliage and flowers. This collected seed was grown out and seedlings selected for superior foliage, flower coverage and flower color. The new variety was identified as a potentially interesting selection in June of 2009, at a greenhouse in Grand Haven, Mich.
Asexual reproduction of the new cultivar ‘SMNSJSP’ by softwood cuttings was first performed during June of 2009, at commercial greenhouse in Grand Haven, Mich. Subsequent propagation has shown that the unique features of this cultivar are stable and reproduced true to type in 3 successive generations.